Owings Mills High School was locked down during the morning after Baltimore County police said a student brought a BB gun to school to show it off. Anne Arundel County police were called to Southern High School in Harwood, where a student was arrested for allegedly having a knife and an unloaded pellet gun.

Baltimore County police spokeswoman Elise Armacost said students spotted a schoolmate removing what appeared to be a gun from his waistband at about 10 a.m. near the school on Tollgate Road. The students reported the weapon to school staff, prompting administrators to put the school on lockdown while police canvassed the area, searching for a gunman.

After reviewing school security footage, police identified the 17-year-old suspect, who Armacost said was in the school's office for unrelated reasons. Officers searched him and said they recovered the Airsoft BB gun. Armacost said he did not fire the weapon.

"It's pretty evident that we do have a plan that works," Armacost said. "What happened today is supposed to happen," she said, praising the students for coming forward.

The teen, who lives in the Owings Mills area, was arrested and charged as a juvenile with possession of a dangerous weapon and disruption of school activities.

Police do not identify suspects charged as juveniles.

A school spokesman said Owings Mills High was placed on lockdown for about 30 minutes and that a telephone message would be sent to parents in the afternoon to brief them on what happened.

In the Southern High incident, Anne Arundel County police said a school resource officer assigned to the school in the 4400 block of Solomons Island Road was told at about 11 a.m. that a student was carrying a weapon and showed it to another student.

The officer located the student in the cafeteria during lunch and reported that he was carrying a knife and a carbon-dioxide-powered pellet gun, which was not loaded and had no cartridge inserted. The weapon was confiscated, police said.

The student was arrested and charged through a juvenile citation with two counts of carrying a dangerous weapon on school property.

The Owings Mills incident is the fourth related to guns in Baltimore County this school year. On the first day of school, a Perry Hall High School student was critically wounded after 15-year-old Robert Gladden Jr. allegedly brought a shotgun to school. He had assembled the gun in a bathroom before opening fire in the cafeteria, police said.

A few days later, a Stemmers Run Middle School student brought a loaded handgun to class and threatened students and his teacher, but no one was injured, officials said.

And earlier this month, two students at Deer Park Middle Magnet had allegedly agreed to exchange a Bersa .380-caliber gun for an Xbox 360 at one boy's house. Police said they became aware of the swap when a school resource officer found a handful of ammunition in jeans left in a school locker room.

Following the incidents, Baltimore County officials have laid out plans to buy hand-held metal detectors for school resource officers and offer free gun locks to residents, and have named a new school safety chief.

Anne Arundel County police recently announced a smart phone application, "AACOPD Speak Out," for students to anonymously email tips to school resource officers. The tip in this case was received by phone.